Instrument for locating a noise source in a CATV system and method of using same

ABSTRACT

An instrument for locating noise in a CATV system is disclosed. The instrument comprises an electrical circuit assembly moveable within an outer body. The electrical circuit assembly includes a filter configured to suppress noise frequencies in the CATV system. The instrument also includes a mechanical biasing element coupled to the electrical circuit assembly to bias the electrical circuit assembly in a position relative to the outer body.

TECHNICAL FIELD

The present disclosure relates generally to cable television (CATV)system installation and maintenance at a subscriber's premises, and,more particularly, to locating a point of ingress of noise into the CATVsystem.

BACKGROUND

The installation of equipment at a subscriber's premises and themaintenance of the physical plant in a CATV system are among the taskstypically assigned to technicians. Technicians typically use leakagemeters, signal level meters, and other equipment to complete thesetasks. For example, technicians have typically used signal level metersto measure the physical properties of signals intended to be present onthe CATV system and also to measure signals that are intruding (ingress)into the system. This is usually done by physically connecting thesignal level meter to a test point in the CATV system.

A technician may also utilize a test probe that may be attached to aport of a distribution tap located at a subscriber's premises, and thetechnician may connect a signal level meter or analyzer to the probe tomeasure forward and reverse signals in the system, as well as ingress.One example of a test probe is shown and described in U.S. Pat. No.6,292,944, which is expressly incorporated herein by reference. Onecommercially available test probe is the I-Stop™ Reverse Test Probe,which is a commercially available from Trilithic, Inc.

SUMMARY

According to one aspect of the disclosure, a system for locating noisein a CATV system is disclosed. The system includes a probe or instrumentconfigured to be coupled to a port of the CATV system. The probe isoperable to selectively filter signals in the CATV system to suppressthe frequencies at which noise may be present in the CATV system. Insome embodiments, the system also includes a signal level meter, and theprobe may be configured to be coupled to the signal level meter todetect and locate noise in the CATV system.

According to another aspect, the instrument for locating noise in a CATVsystem comprises an outer body including a first connector configured tobe coupled to a port of a CATV tap and a second connector configured tobe coupled to a signal level meter. The instrument also includes anelectrical circuit assembly positioned in the outer body. The electricalcircuit assembly includes a filter configured to suppress noisefrequencies in the CATV system and a shaft extending outwardly from thefirst connector to a shaft tip. A mechanical biasing element is coupledto the electrical circuit assembly opposite the shaft. The circuitassembly is moveable within the outer body along a first axis between afirst position at which a first distance is defined between along thefirst axis the shaft tip and an end of the first connector and a secondposition at which a second distance less than the first distance isdefined along the first axis between the shaft tip and the end of thefirst connector. The mechanical biasing element is operable to bias thecircuit assembly in the first position in the outer body.

In some embodiments, the circuit assembly may include a circuit boardhaving a first board section extending into an opening defined in thefirst connector. Additionally, in some embodiments, the instrument mayfurther a sleeve positioned in the first connector between the firstboard section and an inner surface of the first connector toelectrically insulate the first board section from the first connector.

In some embodiments, the shaft may extend from a base connected to thefirst board section through a passageway defined in the sleeve to theshaft tip.

In some embodiments, the instrument may comprise a first shaft coupledto the second connector. The electrical circuit assembly may include asecond shaft arranged telescopically with the first shaft. The firstshaft and the second shaft may cooperate to electrically connect theelectrical circuit assembly with the second connector. Additionally, insome embodiments, the mechanical biasing element may include a springpositioned between an end of the first shaft and a base of the secondshaft.

In some embodiments, the shaft may extend in a first direction to theshaft tip. The second shaft may include an elongated rod that extendsaway from the base in a second direction opposite the first direction.

In some embodiments, the instrument may further comprise a bracketincluding a central opening. The first shaft may be mounted in thecentral opening of the bracket. Additionally, in some embodiments, theouter body may include a housing having a first end coupled to the firstconnector and a second end coupled to the second connector. The housingmay define an inner chamber, and the bracket may be coupled to thehousing within the inner chamber.

In some embodiments, the instrument may further comprise a supportbracket coupled to the housing between the first end and the second end.The support bracket may be configured to prevent rotation of theelectrical circuit assembly about the first axis.

In some embodiments, the instrument may further comprise a user-operatedcontrol extending outwardly from the outer body. The user-operatedcontrol may be operable to electrically connect the filter to the secondconnector and configured to move with the electrical circuit assembly.In some embodiments, the mechanical biasing element may include a pairof telescopic legs coupled to the electrical circuit assembly and theouter body.

In some embodiments, the instrument may include the signal level meter.

According to another aspect, an instrument comprises a housing extendingalong a longitudinal axis from a first end to a second end. The housingincludes an opening defined in the first end and an inner chamber thatextends inwardly from the opening. The instrument comprises a firstconnector threaded onto the first end of the housing, and the firstconnector includes a threaded outer surface configured to engage a portof a CATV tap. The instrument also comprises an electrical circuit boardconfigured to move along the longitudinal axis relative to the housing.The circuit board includes a first board section positioned in the firstconnector, a second board section positioned in the inner chamber of thehousing, and a filter mounted thereon. The filter is configured tosuppress noise frequencies in the CATV system. The instrument alsocomprises a shaft coupled to the first board section and extendingoutwardly along the longitudinal axis from the first connector to ashaft tip, a second connector secured to the second end of the housingand configured to be coupled to a signal level meter, a telescopic shaftconnecting the second connector to the circuit board, and a mechanicalbiasing element attached to the telescopic shaft that is operable tobias the circuit board in a first position within the housing.

In some embodiments, the instrument may further comprise a user-operatedcontrol coupled to the circuit board and extending outwardly from thehousing. The user-operated control may be operable to electricallyconnect the filter to the second connector and may be configured to movewith the circuit board.

In some embodiments, the instrument may further comprise a sleevepositioned in the first connector between the first board section and aninner surface of the first connector to electrically insulate the firstboard section from the first connector.

In some embodiments, the shaft may extend from a base connected to thefirst board section through a passageway defined in the sleeve to theshaft tip.

In some embodiments, the instrument may further comprise a bracketcoupled to an inner wall of the housing at the second end of thehousing. The bracket may include a central opening, and the telescopicshaft may extend through the central opening of the bracket.

In some embodiments, the instrument may include a second mechanicalbiasing element that includes a pair of telescopic legs positioned oneach side of the bracket. Each telescopic leg may extend from a firstend coupled to the second board section of the circuit board to a secondend that engages the inner wall of the housing.

In some embodiments, the instrument may further comprise a supportbracket coupled to the housing between the first end and the second end.The support bracket may be configured to prevent rotation of the circuitboard about the longitudinal axis.

According to another aspect, a method of locating noise in a CATV systemis disclosed. The method comprises aligning a first connector of aninstrument with a port of a CATV tap, engaging the first connector ofthe instrument with the port to position a shaft tip in an aperturedefined in the port, advancing the shaft tip into contact with a testpoint positioned in the aperture to cause a circuit board of theinstrument to move, operating a user-operated control to connect afilter on the circuit board to a signal level meter to suppress noisefrequencies in the CATV system upstream from the port, and determining anoise source based on signals provided through the instrument.

According to another aspect, an electrical circuit assembly for aninstrument for locating noise in a CATV system is disclosed. Theelectrical circuit assembly comprises a printed circuit board includinga first board section sized to be positioned in a connector and a secondboard section, and a filter mounted on the printed circuit board. Thefilter is configured to suppress noise frequencies in the CATV system.The electrical circuit assembly comprises a first shaft coupled to thefirst board section and extending outwardly from the first board sectionin a first direction to a shaft tip, a second shaft extending from thesecond board section in a second direction opposite the first direction,and a spring positioned over the second shaft. A user-operated controlextends outwardly from the printed circuit board and is operable toelectrically connect the filter to the first shaft.

In some embodiments, the electrical circuit assembly may furthercomprise a pair of telescopic legs coupled to the printed circuit board.

In some embodiments, a slot may be defined in the printed circuit board.The first shaft may be positioned in the slot.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description particularly refers to the following figures,in which:

FIG. 1 is a diagram of a CATV system;

FIG. 2 is an exploded view of an instrument system and a distributiontap of the CATV system of FIG. 1;

FIG. 3 is an exploded perspective view of a probe instrument of theinstrument system of FIG. 2;

FIG. 4 is a cross-sectional view of the probe instrument taken along theline 4-4 in FIG. 2 showing the electrical circuit assembly in anunloaded position;

FIG. 5 is a view similar to FIG. 4 showing the electrical circuitassembly in loaded position;

FIG. 6 is a block diagram of the electrical circuit assembly of theprobe instrument of FIG. 2-5; and

FIG. 7 is an exemplary electrical schematic of the electrical circuitassembly of FIG. 6.

DETAILED DESCRIPTION OF THE DRAWINGS

While the concepts of the present disclosure are susceptible to variousmodifications and alternative forms, specific exemplary embodimentsthereof have been shown by way of example in the drawings and willherein be described in detail. It should be understood, however, thatthere is no intent to limit the concepts of the present disclosure tothe particular forms disclosed, but on the contrary, the intention is tocover all modifications, equivalents, and alternatives falling withinthe spirit and scope of the invention as defined by the appended claims.

Referring now to FIG. 1, a CATV system 10 includes a head end 12 whereprogramming material is obtained and modulated onto appropriate carriersfor distribution to subscribers' premises 20. Subscribers' premises mayinclude offices, homes, apartments, or other spaces at which CATVcontent is desired. The carriers may be combined for distributiondownstream to subscribers over what is typically referred to as theforward path. Signals going upstream from subscribers' premises aretypically routed in what is called the return path.

The CATV system 10 includes data lines 14 such as, for example, coaxialcable and/or optical fiber that transport the CATV signals. In someembodiments, the CATV signals are transported as radio frequencies (RF).The signals may also be transported in hybrid systems including opticaltransmission portions in which the RF signals are converted to light forfiber optic transmission over some portions of the signal path and as RFsignals over other portions of the signal path.

A number of amplifiers 16 are positioned throughout the CATV system 10to compensate for signal loss caused by, for example, imperfections inthe data lines or splitting of the signal during distribution. The CATVsystem 10 also includes a plurality of distribution taps 18 that providepoints at which the subscribers' premises 20 may be connected. In theillustrative embodiment, a single distribution tap 18 is connected to asingle subscriber's premises 20 via a coaxial cable 22. It should beappreciated that in other embodiments one or more of the taps may splitthe signals for distribution into two, four, or eight subscribers'premises 20.

Referring now to FIG. 2, the distribution tap 18 includes a number ofports 30 that provide connection points for the data lines 14 of theCATV system 10 and the coaxial cable 22 at the subscriber's premises 20.Each port 30 includes a threaded opening 32 that is defined in thehousing 34 of the distribution tap 18. Each opening 32 is sized toreceive, for example, a F-connector 36 of a coaxial cable coupler orother device. A test point 38, such as, for example, a seizure screw, islocated at the base of each opening 32 to receive and transmit signalsover the CATV system 10. As described in greater detail below, atechnician may connect an instrument system 50 to one of the ports 30 toevaluate the operation of the CATV system 10, including, for example,the amount of ingress noise present at the distribution tap 18.

In the illustrative embodiment, the instrument system 50 includes asignal level meter 52 and a probe instrument 54 configured to be coupledto the meter 52 and one of the unused ports 30 of the distribution tap18. The signal level meter 52 may be, for example, a Trilithic 860 DSPi™signal level meter, which is commercially available from Trilithic, Inc,that is configured to receive signals from the probe 54 and displaythose signals for analysis by the technician. The probe 54 includes anoutput port 56 configured to be coupled to the signal level meter 52. Inthe illustrative embodiment, the port 56 includes a threaded F-connector58 to engage, for example, a coaxial cable connector extending from thesignal level meter 52.

The probe 54 also includes an input port 60 configured to be coupled toa distribution tap 18. In the illustrative embodiment, the input port 60includes a threaded connector 62 to engage the threaded opening 32 ofthe distribution tap 18. As shown in FIG. 2, the probe 54 includes ainput shaft 64 that extends outwardly from the connector 62 to a shafttip 66. As described in greater detail below, the input shaft 64 isconfigured to engage a test point 38 in the distribution tap 18 toselectively connect the electrical circuitry of the probe 54 (and hencethe signal level meter 52) to the CATV system 10. The input shaft 64 iscompressible to accommodate port openings of varying depth to avoiddamage to the electrical circuitry of the probe 54.

Referring now to FIG. 3, the probe 54 is an assembly that includes ahousing 70 and an electrical circuit assembly 72 that is positioned inthe housing 70. The housing 70 extends along a longitudinal axis 74 ofthe probe 54 from a proximal end 76 to a distal end 78. The output port56 is coupled to the proximal end 76 of the housing 70, and the probe 54includes a connector sleeve 80 that couples the output port 56 to theelectrical circuit assembly 72. The connector sleeve 80 isillustratively secured within the housing 70 via a bracket 82. The inputport 60 is coupled to the distal end 78 of the housing 70 and includes apassageway 84 that receives a sleeve 86. In the illustrative embodiment,the sleeve 86 is configured to electrically insulate the input shaft 64of electrical circuit assembly 72 from the input port 60 (and hence theconnector 62).

The connector 62 of the input port 60 includes a base 90 and acylindrical body 92 that extends outwardly from the base 90 to a distalend 94. In the illustrative embodiment, the connector 62 is formed as asingle monolithic component from a metallic material such as, forexample, stainless steel. It should be appreciated that in otherembodiments the connector 62 may be formed from a non-conductive plasticor other polymeric material. The body 92 includes an externally-threadedouter surface 96 that is configured to engage the internally-threadedopening 32 of one of the ports 30 of the distribution tap 18. Theconnector 62 also includes an opening 98 that is defined in the distalend 94 and another opening 100 that is defined in the opposite end ofthe base 90. An inner wall 102 extends between the openings 98, 100 todefine the passageway 84.

As shown in FIG. 3, the inner wall 102 of the connector 62 includes adistal section 104 that extends inwardly from the opening 98 of the body92. The distal section 104 includes a curved inner surface that definesa cylindrical portion 108 of the passageway 84. The inner wall 102 has aproximal section 110 that extends inwardly from the opening 100 in thebase 90. In the illustrative embodiment, the proximal section 110includes a plurality of internal threads 112 that are configured toengage a plurality of external threads 114 defined on the distal end 78of the housing 70 to couple the connector 62 to the housing 70. Itshould be appreciated that in other embodiments the connector may becoupled to the housing via welding, adhesive, or other fastening means.

The inner wall 102 of the connector 62 includes an annular section 116that connects the proximal section 110 to the distal section 104. Asshown in FIGS. 3-4, a central aperture 118 is defined in the annularsection 116, and the cylindrical portion 108 of the passageway 84 opensinto the aperture 118. The annular section 116 of the wall 102 alsoincludes a base surface 120 that surrounds the opening of thecylindrical portion 108. As shown in FIG. 4, the base surface 120 isconfigured to engage a flange 122 of the sleeve 86 when the probe 54 isassembled.

Returning to FIG. 3, the sleeve 86 includes the flange 122, whichextends outwardly from a main body 124. The main body 124 is sized to bepositioned in the cylindrical portion 108 of the passageway 84 of theconnector 62. The sleeve 86 also includes a distal tip 126, which has asmaller diameter and extends from the main body 124. In the illustrativeembodiment, the sleeve 86 is formed as a single monolithic componentfrom a non-conductive plastic, such as, for example, Teflon, capable ofdielectrically insulating the connector 62 from the electrical circuitassembly 72.

An opening 128 is defined in the distal tip 126 of the sleeve 86 andanother opening 130 is defined in the proximal end of the main body 124.An inner wall 132 extends between the openings 128, 130 to define acavity 134 in the sleeve 86. The cavity 134 includes a distal bore 136that extends through the distal tip 126 and opens into an aperture 138.The distal bore 136 is sized to receive the input shaft 64 of theelectrical circuit assembly 72. The cavity 134 also includes a proximalbore 140 that is sized to receive a portion of the circuit board of theelectrical circuit assembly 72, as described in greater detail below.

As described above, the output port 56 is coupled to the proximal end 76of the housing 70 and includes a threaded F-connector 58. In theillustrative embodiment, the connector 58 is formed as a singlemonolithic component from a metallic material such as, for example,brass with gold plating. As shown in FIG. 3, the connector 58 includes abody 142 that has a threaded outer surface 144 configured to engage athreaded opening of a signal level meter 52 and a threaded opening 146of the housing 70. A lock nut 148 secures the body 142 to the housing70, and a central passageway 150 extends through ends of the body 142.

The central passageway 150 is sized to receive an elongated rod 160 ofthe connector sleeve 80. As described above, the connector sleeve 80couples the output port 56 to the electrical circuit assembly 72. In theillustrative embodiment, the connector sleeve 80 includes a shaft 162that extends from a distal end 164 to a proximal end 166. The elongatedrod 160 extends away from the proximal end 166 of the shaft 162 to aproximal tip 168. The connector sleeve 80 also includes a flange 170that extends outwardly from the main shaft 162 between the ends 164,166. The connector sleeve 80 is illustratively formed as a singlemonolithic component from a metallic material such as, for example,brass with gold plating.

As shown in FIG. 4, the connector sleeve 80 includes an opening 172 inthe distal end 164. A bore 174 extends inwardly from the opening 172 toa bottom wall 176. The bore 174 is sized to receive an output shaft 180of the electrical circuit assembly 72, as described in greater detailbelow, to connect the connector sleeve 80 (and hence the outputconnector 58) to the electrical circuit assembly 72. The output shaft180 of the electrical circuit assembly 72 is arranged telescopicallywith the shaft 162 of the connector sleeve 80. A mechanical biasingelement such as, for example, spring 182 is positioned between thedistal end 164 of the connector sleeve 80 and a base 184 of the shaft162. The spring 182 extends over the length of the shaft 162, as shownin FIG. 3. In other embodiments, the mechanical biasing element be takethe form of an elastomeric body or other structure configured operableto bias the circuit board 220 in the unloaded position shown in FIG. 4.

As described above, the probe 54 includes a bracket 82 that secures theconnector sleeve 80 within the housing 70. The bracket 82 has a distalsurface 190 and a proximal surface 192 positioned opposite the distalsurface 190. As shown in FIG. 4, the bracket 82 has a rim wall 194 thatextends inwardly from an opening defined in the proximal surface 192.The rim wall 194 is sized to be positioned over in a groove 196 of thehousing 70 of the probe 54. A central opening 198 sized to receive theshaft 162 of the connector sleeve 80 extends through the bracket 82. Inthe illustrative embodiment, the bracket 82 is formed as a singlemonolithic component from a non-conductive plastic such as, for example,Teflon, capable of dielectrically insulating the connector sleeve 80from the housing 70.

As shown in FIGS. 3-4, the housing 70 of the extends along thelongitudinal axis 74 from the proximal end 76 to the distal end 78. Asdescribed above, the housing 70 has a plurality of external threads 114that are defined on the distal end 78, which are configured to engagethe threads 112 of the connector 62. The distal end 78 also has anopening 200, and an inner wall 202 extends inwardly from the opening 200to a bottom wall 204. The walls 202, 204 cooperate to define an innerchamber 206 sized to receive the electrical circuit assembly 72. Thehousing 70 also includes an oblong slot 208 that opens into one side ofthe chamber 206.

As described above, the housing 70 includes a groove 196 that receivesthe bracket 82. The groove 196 is defined in the bottom wall 204, asshown in FIG. 4. The threaded opening 146, which receives the outputconnector 58, is surrounded by the groove 196.

In the illustrative embodiment, the housing 70 includes a barrel 210 anda cap 212 defines the proximal end 76. As shown in FIG. 4, the cap 212is threaded onto one end of the barrel 210, and includes the bottom wall204 of the housing 70. The barrel 210 and the cap 212 are each formedfrom a metallic material, such as, for example, aluminum. It should beappreciated that in other embodiments the housing 70 may be formed as asingle monolithic component from a metallic material, such as, forexample, aluminum or stainless steel. Additionally, the housing 70, theinput connector 62, and output connector 58 cooperate to define the mainbody of the probe 54. In other embodiments, the main body may be formedby combining the housing and one or more of the connectors into a singlemonolithic component.

As shown in FIG. 4, the probe 54 also includes a support bracket 214that is coupled to the inner wall 202 of the housing 70. The bracket 214includes a pair of planar surfaces that engage the electrical circuitassembly 72 in the inner chamber 206 and prevent the electrical circuitassembly 72 from rotating about the axis 74. In the illustrativeembodiment, the support bracket 214 is formed as a single monolithiccomponent from a non-conductive plastic such as, for example, Teflon,capable of dielectrically insulating the electrical circuit assembly 72from the housing 70.

Returning to FIG. 3, the electrical circuit assembly 72 includes aprinted circuit board (PCB) 220 that has a distal section 222 and aproximal section 224. The electrical circuit assembly 72 also includesthe input shaft 64 extending outwardly from the distal section 222. Theinput shaft 64 extends a fixed length 226 from the distal board section222 to the shaft tip 66. In the illustrative embodiment, the length 226is equal to about 0.550 inches.

As shown in FIG. 4, the distal board section 222 is narrower than theproximal board section 224 and is sized to extend into the proximal bore140 of the insulator sleeve 86 to minimize the length 226 of the inputshaft 64. The proximal section 224 is wider than the diameter of theproximal bore 140 and is thereby prevented from entering the bore 140.

The proximal board section 224 includes a longitudinal slot 228 thatextends inwardly along the axis 74 from its proximal edge. As shown inFIG. 3, the output shaft 180 is positioned in the longitudinal slot 228.The output shaft 180 has a base 184 that is connected to an inner edge230 of the proximal board section 224 and an elongated body 232 thatextends outwardly from the base 184.

The electrical circuit assembly 72 also includes a pair of telescopiclegs 234 that extend proximally from the board section 224. Each leg 234has an end 236 configured to engage the bottom wall 204 of the housing70. The components of each leg 234 are illustratively formed from ametallic material such as, for example, brass with gold plating. Eachleg 234 is also spring-loaded in the illustrative embodiment to assistin biasing the circuit board 220 in the unloaded position shown in FIG.4.

As described in greater detail below, the electrical circuit assembly 72is operated via a user-control 240 that extends outwardly from the PCB220. In the illustrative embodiment, the user-control 240 includes aswitch having a lever arm 242 that extends outwardly from the oblongslot 208 defined in the housing 70. The probe 54 includes a cover 244that is positioned in the slot 208 over the end of the lever arm 242 toprevent moisture or other environmental contaminants from entering theinner chamber 206.

As described above, the input shaft 64 of the probe 54 is compressibleto accommodate port openings of varying depth to avoid damage to theelectrical circuitry of the probe 54. As shown in FIG. 4, the electricalcircuit assembly 72 is initially in an unloaded position, and a distance250 is defined between the shaft tip 66 and the distal end 94 of theconnector 62 along the axis 74. When the probe 54 is coupled to a port30 of a distribution tap 18, the technician engages the input connector62 with the opening 32 and, by threading the connector 62 into theopening, advances the probe 54 deeper into the port 30.

As the probe 54 moves deeper into the port 30, the distal shaft tip 66of the input shaft 64 is advanced into contact with the test point 38(e.g., a seizure screw) and the electrical circuit assembly 72 iscoupled to the CATV system 10. The technician may continue to thread theconnector 62 into the port 30 to bottom the shoulder of the connectorbase 90 against the distribution tap 18. When the technician continuesto thread the connector 62 into the port 30 after the shaft tip 66contacts the test point 38, a load is exerted in the direction indicatedby arrow 252 in FIG. 4 on the shaft 64 (and hence the electrical circuitassembly 72). This load overcomes the bias exerted by the spring 182,and the electrical circuit assembly 72 (including the PCB 220) may moveproximally to the loaded position shown in FIG. 5.

In the loaded position, a distance 254 is defined between the shaft tip66 and the distal end 94 of the connector 62 along the axis 74. Thedistance 254 is less than the distance 250. In the illustrativeembodiment, the distance between the shaft tip 66 and the shoulder ofthe connector base 90 between the unloaded and the loaded positiondecreases by the same amount.

When the input shaft 64 of the probe 54 contacts the test point 38(e.g., a seizure screw) and the electrical circuit assembly 72 iscoupled to the CATV system 10, the user may operate the user-control 240(e.g., switch) to connect a filter circuit 302 of the electrical circuitassembly 72. If connecting the filter circuit 302 causes the measuredingress to decrease by, for example 4 to 6 dB, then the source of theingress is further downstream in the CATV system 10. If connecting thefilter circuit 302 does not cause the measured ingress to decrease, thenthe source of the ingress is upstream in the CATV system 10. Byproceeding along the data lines 14, the technician may locate andisolate the ingress noise source.

As shown in FIG. 5, the electrical circuit assembly 72 includes acoupling circuit 300 on the PCB 220 that is connected to the input shaft64 and the output shaft 180. The coupling circuit 300 is configured toattenuate the signals received from the CATV system 10 before supplyingthose signals to the meter 52 coupled to the output port 56. In theillustrative embodiment, the coupling circuit 300 is configured toprovide attenuation that reduces the amplitude of the signals receivedat the input port 60 by about 20 dB before supplying those signals tothe output port 56. The frequencies of the signals attenuated by thecircuit 300 are in a range of about 5 MHz to about 1.2 GHz. As usedherein, the term “about” refers to fifteen percent tolerance based onmanufacturing variation and other design criteria. As such, the phrase“about 5 MHz,” for example, encompasses 4.25 MHz, while the phrase“about 1.2 GHz” includes 1380 MHz.

As described above, the electrical circuit assembly 72 also includes afilter circuit 302, which is selectively coupled to the input shaft 64(and hence the input port 60 and the CATV system 10) by the switch 240.In the illustrative embodiment, the filter circuit 302 is configured toattenuate signals in a frequency range of about 5 MHz to about 30 MHzThis frequency range corresponds to the return path frequencies at whichnoise ingress signals might be present in the CATV system 10 (i.e., thenoise frequencies of the CATV system). In other words, when the filtercircuit 302 is coupled to the input shaft 64 (i.e., when the switch 240is toggled), signals in the frequency range of 5 MHz to 30 MHz aresuppressed in the CATV system 10. If the CATV headend 12 registers adecrease in ingress of 4 to 6 dB, the noise source is farther from thehead end 12 that the test location. The technician may monitor thechange in ingress using the signal level meter 52, which receivestelemetry from the headend 12 via the probe instrument 54. In otherembodiments, the frequency range of the filter circuit 302 may be in arange of about 5 MHz to 42 MHz. It should be appreciated that in otherembodiments the filter may be designed to permit signals in the noiseingress frequency range to pass to the signal level meter 52 andsuppress or attenuate signals at other frequency ranges.

In the illustrative embodiment, the electrical circuit assembly 72 alsoincludes AC and DC blocking circuits 304, 306. The blocking circuit 304,which is included in the coupling circuit 300, is configured to preventexcessive power from being transmitted from the CATV system 10 to thesignal level meter 52. It should be appreciated that in otherembodiments the blocking circuit 304 may be omitted. The blockingcircuit 306 is configured to prevent excessive power from beingtransmitted from the CATV system 10 to the filter circuit 302.

The electrical circuit assembly 72 also includes a high frequency blockcircuit 308 so that the filter circuit 302 does not affect signalspresent on the CATV when the probe 54 is connected to the tap 18. Inthat way, the filter circuit 302 only affects signals present on theCATV in the frequency range of 5 to 30 MHz when the button 242 isdepressed and the filter circuit 302 is coupled to the block circuit 308(which is coupled to the CATV system via the tip of pin 66).

As shown in FIG. 6, the telescopic legs 234 ground the circuitry byconnecting the circuit board 220 to the bottom wall 204 of the housing70. It should be appreciated that in other embodiments a wire, pin, orother structure may be used to ground the board 220.

An exemplary schematic of the circuits 300, 302, 304, 306, 308 is shownin FIG. 7. In the illustrative embodiment, the circuit 300 is configuredto provide an insertion loss at about 1.2 GHz of about 1.5 dB betweenthe input port 60 and the output port 56. It should be appreciated thatother arrangements of the circuits 300, 302, 304, 306 may be used toadjust the amount of attenuation and the bandwidth of the filtercircuit. Additionally, in other embodiments, the circuit 300 may beomitted.

As shown in FIG. 7, the circuit 300 includes a 39 nH inductor 310 thatis coupled to the input shaft 64. The circuit 308 includes a 1 kΩresistor 312 in parallel with a 250 nH inductor 314, which are alsocoupled to the input shaft 64. In the illustrative embodiment, theinductors 310, 314 and the resister 312 are positioned on the distalboard section 222 to position those elements close to the input shaft 64and thereby permit the circuitry to operate effectively up to about 1.2GHz.

As described above, this application discloses, among other things, amethod of locating noise in a CATV system that comprises aligning afirst connector of an instrument with a port of a CATV tap, engaging thefirst connector of the instrument with the port to position a shaft tipin an aperture defined in the port, advancing the shaft tip into contactwith a test point positioned in the aperture to cause a circuit board ofthe instrument to move, operating a user-operated control to connect afilter on the circuit board to a signal level meter to suppress noisefrequencies in the CATV system upstream from the port, and determining anoise source based on signals provided through the instrument.

This application also discloses, among other things, an electricalcircuit assembly for an instrument for locating noise in a CATV systemthat comprises a printed circuit board including a first board sectionsized to be positioned in a connector and a second board section, afilter mounted on the printed circuit board that is configured tosuppress noise frequencies in the CATV system, a first shaft coupled tothe first board section and extending outwardly from the first boardsection in a first direction to a shaft tip, a second shaft extendingfrom the second board section in a second direction opposite the firstdirection, a spring positioned over the second shaft, and auser-operated control extending outwardly from the printed circuitboard. The user-operated control is operable to electrically connect thefilter to the first shaft. The electrical circuit assembly may furthercomprise a pair of telescopic legs coupled to the printed circuit board.A slot may be defined in the printed circuit board, and the first shaftmay be positioned in the slot.

While the disclosure has been illustrated and described in detail in thedrawings and foregoing description, such an illustration and descriptionis to be considered as exemplary and not restrictive in character, itbeing understood that only illustrative embodiments have been shown anddescribed and that all changes and modifications that come within thespirit of the disclosure are desired to be protected.

There are a plurality of advantages of the present disclosure arisingfrom the various features of the method, apparatus, and system describedherein. It will be noted that alternative embodiments of the method,apparatus, and system of the present disclosure may not include all ofthe features described yet still benefit from at least some of theadvantages of such features. Those of ordinary skill in the art mayreadily devise their own implementations of the method, apparatus, andsystem that incorporate one or more of the features of the presentinvention and fall within the spirit and scope of the present disclosureas defined by the appended claims.

The invention claimed is:
 1. An instrument for locating noise in a CATVsystem, the instrument comprising: an outer body including a firstconnector configured to be coupled to a port of a CATV tap and a secondconnector configured to be coupled to a signal level meter, anelectrical circuit assembly positioned in the outer body, the electricalcircuit assembly including a filter configured to suppress noisefrequencies in the CATV system and a shaft extending outwardly from thefirst connector to a shaft tip, and a mechanical biasing element coupledto the electrical circuit assembly opposite the shaft, wherein theelectrical circuit assembly is moveable within the outer body along afirst axis between (i) a first position at which a first distance isdefined along the first axis between the shaft tip and an end of thefirst connector and (ii) a second position at which a second distanceless than the first distance is defined along the first axis between theshaft tip and the end of the first connector, and wherein the mechanicalbiasing element is operable to bias the electrical circuit assembly inthe first position in the outer body.
 2. The instrument of claim 1,wherein the electrical circuit assembly includes a circuit board havinga first board section extending into an opening defined in the firstconnector.
 3. The instrument of claim 2, further comprising a sleevepositioned in the first connector between the first board section and aninner surface of the first connector to electrically insulate the firstboard section from the first connector.
 4. The instrument of claim 3,wherein the shaft extends from a base connected to the first boardsection through a passageway defined in the sleeve to the shaft tip. 5.The instrument of claim 1, further comprising a first shaft coupled tothe second connector, wherein the electrical circuit assembly includes asecond shaft arranged telescopically with the first shaft, the firstshaft and the second shaft cooperating to electrically connect theelectrical circuit assembly with the second connector.
 6. The instrumentof claim 5, wherein the mechanical biasing element includes a springpositioned between an end of the first shaft and a base of the secondshaft.
 7. The instrument of claim 6, wherein the shaft extends in afirst direction to the shaft tip, and the second shaft includes anelongated rod that extends away from the base in a second directionopposite the first direction.
 8. The instrument of claim 5, furthercomprising a bracket including a central opening, wherein the firstshaft is mounted in the central opening of the bracket.
 9. Theinstrument of claim 8, wherein: the outer body includes a housing havinga first end coupled to the first connector and a second end coupled tothe second connector, the housing defining an inner chamber, and thebracket is coupled to the housing within the inner chamber.
 10. Theinstrument of claim 9, further comprising a support bracket coupled tothe housing between the first end and the second end, the supportbracket configured to prevent rotation of the electrical circuitassembly about the first axis.
 11. The instrument of claim 1, furthercomprising a user-operated control extending outwardly from the outerbody, the user-operated control being operable to electrically connectthe filter to the second connector and configured to move with theelectrical circuit assembly.
 12. The instrument of claim 1, wherein themechanical biasing element includes a pair of telescopic legs coupled tothe electrical circuit assembly and the outer body.
 13. The instrumentof claim 1, further comprising the signal level meter.
 14. An instrumentfor locating noise in a CATV system, the instrument comprising: ahousing extending along a longitudinal axis from a first end to a secondend, the housing including an opening defined in the first end and aninner chamber that extends inwardly from the opening, a first connectorthreaded onto the first end of the housing, the first connectorincluding a threaded outer surface configured to engage a port of a CATVtap, an electrical circuit board configured to move along thelongitudinal axis relative to the housing, the electrical circuit boardincluding a first board section positioned in the first connector, asecond board section positioned in the inner chamber of the housing, anda filter mounted thereon, the filter configured to suppress noisefrequencies in the CATV system, a shaft coupled to the first boardsection and extending outwardly along the longitudinal axis from thefirst connector to a shaft tip, a second connector secured to the secondend of the housing and configured to be coupled to a signal level meter,a telescopic shaft connecting the second connector to the electricalcircuit board, and a mechanical biasing element attached to thetelescopic shaft that is operable to bias the electrical circuit boardin a first position within the housing.
 15. The instrument of claim 14,further comprising a user-operated control coupled to the electricalcircuit board and extending outwardly from the housing, theuser-operated control being operable to electrically connect the filterto the second connector and being configured to move with the electricalcircuit board.
 16. The instrument of claim 14, further comprising asleeve positioned in the first connector between the first board sectionand an inner surface of the first connector to electrically insulate thefirst board section from the first connector.
 17. The instrument ofclaim 16, wherein the shaft extends from a base connected to the firstboard section through a passageway defined in the sleeve to the shafttip.
 18. The instrument of claim 14, further comprising a bracketcoupled to an inner wall of the housing at the second end of thehousing, wherein the bracket includes a central opening, and thetelescopic shaft extends through the central opening of the bracket. 19.The instrument of claim 18, further comprising a second mechanicalbiasing element including a pair of telescopic legs positioned on eachside of the bracket, each telescopic leg extending from a first endcoupled to the second board section of the electrical circuit board to asecond end that engages the inner wall of the housing.
 20. Theinstrument of claim 14, further comprising a support bracket coupled tothe housing between the first end and the second end, the supportbracket being configured to prevent rotation of the electrical circuitboard about the longitudinal axis.